Conventional mathematical software is available to run on personal computers and high-end handheld graphing calculators. These pieces of mathematical software are capable of performing symbolic and numeric calculations. Symbolic calculation refers to the calculation carried out using signs that represent operations, quantities, elements, relations, or qualities without any approximation or rounding errors. Numbers that cannot be represented precisely as integer or floating point numbers are represented as symbols. Unknown variables representing an unknown quantity are allowed to participate in calculations as symbols. This is the basis for the generalization of arithmetic in which letters represent numbers. Mathematical rules are applied during symbolic calculation to simplify the input.
Numeric calculation refers to calculations carried out in which quantities are known, in either integer or floating point number format. Numeric calculations cannot include unknown variables. In many cases rounding errors will occur and the result is approximate rather than exact. There are two reasons for rounding errors to occur. First, some numbers cannot be precisely represented as either integer or floating point numbers. For example, the square root of 2 cannot be represented precisely with a limited number of digits (1.4142135623730950488016887242097 . . . ). In this case, any representation of such a number in integer or floating point numbers is approximate with rounding errors.
Second, if there is a limitation in the number of digits in floating point numbers, certain calculations will exceed the limitation causing truncation to occur, which makes the result approximate because of rounding errors. Here is an example to illustrate this situation: assume floating point numbers are limited to containing at most four decimal digits. In such a case, the mathematical expression “1000+0.1” will result in 1000 because the exact result 1000.1 exceeds the four decimal digits limitation, causing truncation and the loss of the insignificant part of the number. In calculators and computers today, floating point numbers can carry many more digits, but because of finite memory resources, there will always be a limit, regardless of memory size.
There is a relationship between a symbolic calculation and its corresponding numeric calculation. Many users of conventional mathematical software would gain better mathematical insight into this relationship if a symbolic result could be contemporaneously displayed with the numeric result. However, conventional mathematical software does not display both symbolic and numeric results at the same time in response to users' input. Conventional mathematical software, if it has the capability, typically displays the symbolic result by default. Only when the user issues a special command does the numeric result display, in which case the numeric result supplants the display of the symbolic result. FIG. 1 illustrates this problem.
As illustrated in FIG. 1, a mathematical expression 102, such as sin (45), can be entered into a calculator 104. Sine is one of the fundamental trigonometric ratios in mathematics. In a right-sided triangle, the value of the sine (usually abbreviated as “sin”) of an acute angle is equal to the length of the side of the triangle opposite the angle divided by the length of the hypotenuse. Using a conventional calculator, such as the calculator 104, the mathematical expression sin (45) is resolved into a symbolic result 106
      (          1              2              )    .A beginner in mathematics cannot readily appreciate the meaning of the symbolic result
  (      1          2        )without seeing a corresponding numeric result. To resolve the symbolic result
  (      1          2        )to a numerical result, a user of the calculator 104 issues a special command, such as by pushing a specific button on the calculator 104, to cause the symbolic result
  (      1          2        )to resolve to the numeric result 108 “0.707107”. There is a relationship between the symbolic result 106
  (      1          2        )and the numeric result 108 “0.707107,” but conventional calculator 104 would jettison the display of the symbolic result to show the numeric result. Thus, it is difficult for beginners in mathematics to appreciate the relationship between symbolic results and numeric results.